A planet with a severely polluted atmosphere that Amanda Rogers secretly restored using her Q powers.
Tagra IV is an inhabited world whose atmosphere has been badly damaged by pollution, and the Enterprise is assisting with efforts to clean it. The mission brings the young Starfleet intern Amanda Rogers aboard the ship at a moment when her hidden nature is beginning to surface.
In True Q, the young intern Amanda Rogers learns that she is a member of the Q Continuum. Before she leaves with Q, she uses her powers to clear the pollution from Tagra IV as a parting gift.